磷酸铁的湿法磷酸制备及其对合成的磷酸铁锂性能的影响

以湿法磷酸和硫酸亚铁分别为磷源和铁源,通过合成、沉淀过程制备磷酸铁,研究了不同摩尔投料比对合成磷酸铁质量的影响,并以制备的磷酸铁为磷源和铁源采用溶胶凝胶法制备了磷酸铁锂材料.采用了X射线衍射、扫描电子显微镜等手段对合成的磷酸铁锂材料结构和微观形貌进行表征,同时考察了其电化学性能.结果表明：在湿法磷酸和硫酸亚铁摩尔比为1∶1时合成出的磷酸铁中磷质量分数为16.38％,铁质量分数为29.30％,得到的产物最为接近二水磷酸铁;用该磷酸铁制备的磷酸铁锂正极材料在0.1C倍率下充放电,其首次放电比容量达144.4 mAh/g,40次充放电循环后放电容量能达到141.6 mAh/g,衰减率为1.94％,循环倍率性能优良.

Wet-process phosphoric acid for preparation of iron phosphate and its influence on performance of lithium iron phosphate synthesis

Iron phosphate was prepared using wet-process phosphoric acid as phosphorus source and ferrous sulfate as iron source through the synthesis and precipitation process.The influence of different molar weight ratio on the quality of synthetic iron phosphate was studied,and lithium iron phosphate anode material prepared using iron phosphate as the phosphorus source and iron source through the method of sor-gel.Structure and microstructure of the lithium iron phosphate material were characterized by X-ray diffraction and scanning electron microscope,and its electrochemical properties also were investigated.The results show that the phosphorus content of the prepared iron phosphate is 16.38％ and iron content is 29.30％ when the molar ratio of wet-process phosphoric acid and ferrous sulfate is 1：1,the product closing to two water＇s iron phosphate.The lithium iron phosphate anode material prepared using the iron phosphate was chargeddischarged under 0.1C ratio,its first specific discharge capacity reaching up to 144.4 mAh/g.Finally the discharge capacity reaches to 141.6 mAh/g.and the attenuation rate is 1.94％ after 40 times charge-discharge cycle,which demonstrates a excellent performance circulating rate.